Multiple EVSE Installation with Power Sharing System for EVSE Pairs Sharing a Circuit Breaker

ABSTRACT

A multiple EVSE installation employs a power sharing system for EVSE pairs which share a common circuit breaker. When only one EVSE is connected to an electric vehicle for charging, the connected EVSE is allowed to charge at full capacity. When a second EV connects to the second EVSE of the pair, while the first EVSE is charging, a controller senses the latter event and issues commands to both EVSE units to limit their current so that the rated circuit breaker capacity is not exceeded. The controller continuously monitors the charging of each of the EVSE units and sends commands to adjust the supply of current to each EVSE accordingly.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of U.S. Provisional PatentApplication No. 62/008,585 filed on Jun. 6, 2014, the entirety of whichis incorporated herein by reference.

BACKGROUND

This disclosure relates generally to electric vehicle supply equipment(EVSE) installations for charging an electric vehicle (EV). Moreparticularly, this disclosure relates to methods and equipment forsharing and allocating power among multiple EVSE units.

The disclosure addresses an EVSE installation wherein two EVSE unitsshare a common power line and a circuit breaker. In one disclosedapplication, the disclosure illustrates how the power utilized by eachEVSE is effectively and efficiently controlled when two EVSE units aresharing a common circuit breaker, such as, for example, a 40 A circuitbreaker. Pursuant to standard practice, the continuous power supplied bythe breaker is 80% of its rated capacity—which is 32 A for a 40 Acircuit breaker.

The ideal situation is for each Level 2 (30 A) EVSE to have its owndedicated 40 A circuit breaker. This is not always possible or practicalfor existing installations where there is already an existing EVSE andit is desired to add another EVSE to increase the number of chargingparking spaces or situations wherein vehicles may be parked at the EVSEstation for an extended time period. In many cases, one EV being chargedmay not be utilizing the full 30 A charge current available, and theremaining charge capacity could be utilized by a second EVSE to chargean additional EV.

SUMMARY

Briefly stated, a method for sharing power between a first EVSE and asecond EVSE sharing a circuit breaker having a pre-established currentrating and a reduced current capacity comprises connecting a first EVSEto an EV to begin a charge. The method involves charging a first EVSE ata charge limited by the current capacity while the second EVSE is notconnected to an EV and then connecting the second EVSE to an EV to begina charge. The method comprises transmitting a command to the first EVSEand the second EVSE to limit the charge of each to no more than one halfof the current capacity. If either the first EVSE or the second EVSEstops charging, transmitting a restore command to charge the first EVSEor the second EVSE, that does not stop charging at a charge limited bythe current capacity. The method further comprises the step wherein at apre-established time after charging the second EVSE, evaluating thecharge current of the first EVSE and the second EVSE. If the chargingcurrent of the first EVSE or the second EVSE is below one half of thecurrent capacity, a reduce command is transmitted to one of the firstEVSE or the second EVSE and an increase command to the other of thefirst EVSE or the second EVSE, respectively, to reduce and increase thecharge to the one or the other EVSE, respectively.

In one embodiment, the method further comprises replicating theforegoing method for multiple pairs of a first EVSE and a second EVSE. Asingle controller controls all of the EVSE units for multiple pairs of afirst EVSE and a second EVSE. In one embodiment, the method comprisescompiling a running log of power drawn by the first and the second EVSEunits. The ambient temperature may be sensed and the current capacity iscorrespondingly reduced. The method may also comprise automaticallyreducing the current capacity during peak power demand and/orautomatically terminating power during a pre-established time period.

An EVSE installation is connected to a circuit breaker having apre-established current rating and a reduced current capacity comprisingthe first EVSE having a first current control and connectible for powercommunication with the circuit breaker and a second EVSE having a secondcurrent control and being connectable for power communication with thecircuit breaker. An installation controller issues command signals tothe first and the second current controls. A first sensor senses thepower drawn by the first EVSE and communicates with the installationcontroller. A second sensor senses the power drawn by the second EVSEand communicates with the installation controller. The installationcontroller transmits a command to the first EVSE and a command to thesecond EVSE to limit the charge to no more than one half of the currentcapacity when the first EVSE and the second EVSE are connected forcharging. The installation controller issues a restore command to thefirst EVSE to charge one EVSE at a charge limited by the currentcapacity while the other EVSE is not connected to an EV or has stoppedcharging. The installation controller at a pre-established time aftercharging a second EVSE evaluates the charge current sent by the firstsensor and the second sensor so that the charging current of one of thefirst EVSE or the second EVSE is below one half the current capacity.The installation controller transmits a reduce command to the EVSE andan increase command to the other EVSE to charge each EVSE at a reducedcurrent charge and an increased current charge, respectively.

The first and second current control preferably has a range ofapproximately 6 amps to 30 amps. The installation controller ispreferably disposed at a pay station module or a gateway module. In oneembodiment, an integrated installation comprises a multiplicity of EVSEinstallations each comprising a pair of EVSE units connected to a commoncircuit breaker.

A single installation controller controls preferably all of the EVSEunits. A pay station module or gateway module communicates over a Zigbeemesh network with the first and the second EVSE units.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an annotated network block diagram for an integratedmulti-locational electric vehicle charging installation which employsmultiple EVSE stations and a power sharing system for at least some ofthe EVSE stations;

FIG. 2 is an enlarged annotated network block diagram for a portion ofthe EV charging installation of FIG. 1;

FIG. 3 is an annotated elevational view, partly in diagram form, of aportion of the EV charging installation of FIG. 1;

FIG. 4 is an annotated block diagram of a representative portion of anEV charging installation illustrating the operation of the power sharingsystem; and

FIG. 5 is a flowchart illustrating representative operational stepsemployed by the power sharing system.

DETAILED DESCRIPTION

With reference to FIG. 1, an integrated electric vehicle charginginstallation which incorporates multiple EVSE stations and multiplecharging locations and employs a power sharing system is generallydesignated by the numeral 100.

The disclosed intelligent power sharing system is a major step forwardin the pursuit of reducing the electric power infrastructure cost. Thisis achieved by recognizing that all electric vehicle service equipment(EVSE) are not providing the maximum rated current at the same time andby organizing EVSE units in power sharing pairs.

The FIG. 1 representative EV charging installation 100 is intended to beillustrative of various possible applications and configurations for apower sharing system as disclosed below. The EV charging installationincludes multiple payment modules 110 which present multiple transactionmodes to interface with a vehicle user to access electric power and topay for the consumed power. The payment modules 110, for example,preferably have a credit card or a debit card reader and ascreen/keyboard and connect over the Ethernet with a network 130 whichcommunicates with the credit card processor 140. Selected paymentmodules 110 communicate over a Zigbee mesh network with a pair ofadjacent EVSE units 120 and 122 which share power for charging connectedEVs.

For some applications, a standalone payment module 110 communicates witha communication cabinet 114 that provides external communication overthe Ethernet or by various hardwired connection systems with gatewaymodules 112. The gateway modules 110 may connect with various tandempower sharing EVSE units 120 and 122 throughout the installationfacility. The cabinet 114 houses a network router 116 which communicateswith a network controller 118 and also externally with the network 130to provide the various communication links. The network 130 alsopreferably connects with an administrator 150 and a service center 160for the installation.

With additional reference to FIG. 3, a payment module 110 for someinstallation configurations is mounted to a support 170 for a solarpanel 172 to provide sufficient power for communication and transactionpurposes. One or more gateway modules 112 are mounted to a tower 180 forbi-directional wireless communication. It should be appreciated that thecharging power for the various EVSE units is preferably transmittedthrough hardwired conduits which are disposed under the surface of theinstallation.

In a simplified explanatory embodiment illustrated in FIG. 4 fordescriptive purposes, an IPS controller 200 is designed to communicatewith EVSE units connected to a single transformer 210 and multipleservice panels 220. The IPS controller 200 is programmed with themaximum rating for each of the components in the power distributionstructure i.e., the primary transformer 210, service panels 220, breaker230, and EVSE units. FIG. 4 illustrates two EVSE pairs. In oneembodiment, the IPS controller 200 is configured to communicate with asmany as 128 EVSE units.

The major cost reduction is achieved by grouping two EVSE units to shareone breaker. This grouping reduces the cost of the electrical equipmentby half while providing twice as many EVSE for the users. Even thoughthe power source is effectively reduced to one-half, chargingperformance is minimally affected. This is achieved by an efficientapproach wherein the IPS controller 200 continuously communicates witheach EVSE on the power network.

The IPS controller 200 compiles a running log of current being drawn byeach EVSE. When an additional electric vehicle is connected to an unusedEVSE, the EVSE reports to the IPS controller 200 that it has a connectedvehicle and is requesting power. The IPS controller 200 first checks tosee how much current the companion EVSE is drawing. If the current isless than half the rating of the shared breaker i.e., a 40 amp breakercan supply 32 amps continuously and if the first EVSE is drawing 16 ampsor less, the IPS controller 200 instructs the first EVSE to signal (viathe pilot) the electric vehicle that only 16 amps are available. The IPScontroller 200 then checks to see if allowing the second EVSE to add theadditional 16 amps to the branch circuit will cause either the servicepanels or supply transformer to exceed their maximum rating. If not,then the second EVSE is allowed to turn on the power to the electricvehicle, and signal that vehicle, (via its pilot), that 16 amps areavailable.

When the first electric vehicle is fully charged and is drawing aminimum amount of current, the EVSE signals the IPS controller 200 thatthe charge is completed and it has signaled the connected electricvehicle that only standby current is available, typically 5 amps. TheIPS controller 200 then instructs the companion EVSE that additionalcurrent is available (i.e., up to 27 amps). The companion EVSE thennotifies (via the pilot) the connected electric vehicle that additionalpower is available.

In a preferred embodiment, the current is measured by a separate circuitin each EVSE. The measuring current is reported to the payment stationor gateway module for bi-directional controller communicator with IPS200 which in turn transmits a message back to the EVSE to increase orreduce the current supplied to the EVSE.

When the first electric vehicle is completely removed from the firstEVSE, a signal is sent from the first EVSE to the IPS controller 200 ofthe event. The IPS controller 200 then signals the companion EVSE thatthe full power is available, i.e., up to 32 amps.

Because the IPS controller 200 is continuously monitoring the currentbeing drawn by all EVSE units on its network, it will recognize when oneor more components are approaching their maximum rating. When a maximumrating is reached, the IPS controller will instruct all associated EVSEunits to reduce their available power by a percentage until the power isin the operating range.

The IPS controller 200 has multiple capabilities and transmitsappropriate commands to the EVSE units based on numerous inputs. The IPScontroller 200 monitors ambient temperature and reduces the maximumoperating range as the ambient temperature rises. The IPS controller 200also monitors the current being drawn on each phase of the 3 phasetransformer. When the current drawn on one phase substantially exceedsthe current drawn on the other phases, the IPS controller will instructeach EVSE on the one loaded phase to reduce the available power by acalculated percentage to bring that phase into balance.

The IPS controller 200 can be programmed to reduce the overall poweravailable during peak periods. It can also be programmed to turn off allEVSE units during the evenings or on weekends.

The IPS controller 200 can also respond to signals received from remoteDemand Response Application Servers (DRAS).

With additional reference to FIG. 4, a representative tandem EVSEstation 10, which communicates with a payment module 110 or a gatingmodule 112, is generally designated by the numeral 10. A second tandemEVSE station is designated generally by the numeral 12. EVSE station 10comprises a first EVSE unit and a second EVSE unit designated as EVSE 20and EVSE 22, respectively. A single power line 32 connects via a circuitbreaker 230 to provide a source of power to the EVSE station 10. TheEVSE station 10 communicates with controller 200 which is responsive tovarious inputs from each of the EVSE units 20 and 22 to control thecharge current for the tandem EVSE units. The controller 200 providescommand signals to a power control for each of the respective EVSE units20 and 22 to allocate the power between EVSE 20 and EVSE 22 in anefficient manner as required for charging the electric vehicles.

Each EVSE will default to its full 30 A capacity when it is notconnected to the EV. The controller 200, which may be incorporated in apayment station 110 or a gateway 112, has a knowledge of which EVSEpairs (e.g., EVSE 20 and EVSE 22 for station 10; EVSE 24 and EVSE 26 forstation 12) are sharing a breaker and the breaker size. In most cases,the size of the shared circuit breaker is 40 A. The controller 40functions to manage the power utilized by each EVSE such that the totalcurrent drawn by the pair of EVSE units does not exceed the 80% capacityof the circuit breaker (which, for a 40 A breaker, is 32 A). Naturally,if the EVSE units are sharing a 50 A breaker; the total current cannotexceed 40 A.

A new command is added to the command settings of EVSE 20 and EVSE 22 sothat each EVSE can be limited to a specific charge current value. Therange in current setting values is preferably from 6 A to 30 A.

Representative steps for an EVSE station with two power sharing EVSEunits illustrating the power sharing system is illustrated in theflowchart of FIG. 5. It should be appreciated that multiple EVSEstations are preferably controlled by the IPS controller 200. The powersharing system for an EVSE station comprising an EVSE 20 and itscompanion EVSE 22 is described below.

Representative EVSE Control Sequence:

-   1. One of the EVSE units is connected to an EV and begins to charge.    The other EVSE unit of the breaker-sharing pair is not connected to    an EV so the connected EVSE is allowed to charge at its full    capacity of 30 A. For descriptive purposes, the charging EVSE is    arbitrarily designated as EVSE 20 and the non-charging EVSE is    arbitrarily designated as EVSE 22. The controller 200 does not    effectively intervene in the charging levels at this stage.-   2. Another EV pulls up and is connected to the second EVSE 22 while    the first EVSE 20 is charging. The controller 200 senses the latter    event and sends a command to both EVSE 20 and EVSE 22 to limit their    current to 16 A (so that the circuit breaker capacity is not    exceeded).-   3. Subsequently, if either EVSE stops charging, either due to being    unplugged from the EV or the EV being fully charged, the controller    200 will restore the EVSE that is still actively charging to its    full capacity of 30 A.-   4. If the communication is lost between the controller 200 and an    EVSE, the EVSE will default to 16 A. The controller 200 will also    default the other shared EVSE to 16 A to prevent the capacity of    breaker 230 from being exceeded.    Enhanced Representative EVSE Control Sequence with Charge    Optimization:

When both EVSE 20 and EVSE 22 sharing the breaker are actively charging,it is possible that one or the other of the connected EV will not beutilizing the full 16 A allocated to it. For example, one EV may only beusing 12 A. This allows the other EVSE to utilize the remaining 20 A.

A sequence for charge optimization when sharing a 40 A breaker isdetailed below:

-   1. When both EVSE 20 and EVSE 22 are actively charging EVs, and at    least three minutes have elapsed since the last EV was connected for    charging, the charge currents from both EVSE units are evaluated by    the controller 200 to determine if they could be optimized.-   2. If neither EV is drawing the full 16 A allocated to it, the    controller 200 does not need optimize the charge limits of each EVSE    beyond the initial 16 A setting.-   3. If one EVSE is drawing only 12 A and the other EVSE is drawing    the full 16 A allocated to it, the EVSE that is drawing 12 A should    have its current limit reduced to 12 A by the controller 200    transmitting an appropriate command to the EVSE current control, and    the other EVSE should have its current limit raised to 20 A by the    controller 200 transmitting an appropriate command to the companion    EVSE current control.-   4. This will allow the EV that potentially could use more than 16 A    have more charge current available for charging when not required by    the other EV.-   5. The charge currents for each of EVSE 20 and EVSE 22 are    periodically evaluated and compared by the controller 200, and    adjusted as described above.

While preferred embodiments of the foregoing have been set forth forpurposes of illustration, the foregoing description should not be deemeda limitation of the invention herein. Accordingly, variousmodifications, adaptations and alternatives may occur to one skilled inthe art without departing from the spirit and the scope of the presentinvention.

1. A method for sharing power between a first EVSE and a second EVSEsharing a circuit breaker having a pre-established current rating and areduced current capacity comprising: connecting a first EVSE to an EV tobegin a charge; charging said first EV at a charge limited by thecurrent capacity while the second EVSE is not connected to an EV;connecting said second EVSE to an EV to begin a charge; transmitting acommand to the first EVSE and the second EVSE to limit the charge ofeach to no more than one-half the current capacity; if either the firstEVSE or the second EVSE stops charging, transmitting a restore commandto charge the first EVSE or the second EVSE that does not stop chargingat a charge limited by the current capacity; at a pre-established timeafter charging the second EVSE, evaluating the charge current of thefirst EVSE and the second EVSE; if the charging current of the firstEVSE or the second EVSE is below one-half the current capacity,transmitting a reduce command to one of the first EVSE or the secondEVSE and an increase command to the other of the first EVSE or thesecond EVSE, respectively, to reduce and increase the charge to the oneand the other EVSE, respectively.
 2. The method of claim 1 furthercomprising replicating the method for multiple pairs of a first EVSE anda second EVSE.
 3. The method of claim 2 wherein a single controllercontrols all of the EVSE units.
 4. The method of claim 1 furthercomprising compiling a running log of power drawn by the first and thesecond EVSE units.
 5. The method of claim 1 further comprising sensingambient temperatures and correspondingly reducing the current capacity.6. The method of claim 1 further comprising automatically restructuringthe current capacity during periods of peak power demand.
 7. The methodof claim 1 further comprising automatically terminating power duringpre-established time periods.
 8. The method of claim 1 furthercomprising measuring the current at each EVSE.
 9. The method of claim 1further comprising transmitting current measurements to a controllerwhich transmits command signals back to said first and second EVSEunits.
 10. An EVSE installation connected to a circuit breaker having apre-established current rating and a reduced current capacitycomprising: a first EVSE having a first current control and connectablefor power communication with said circuit breaker; a second EVSE havinga second current control and connectable for power communication withsaid circuit breaker; an installation controller which issues commandsignals to said first and said second current controls; a first sensorfor sensing the power drawn by said first EVSE and communicating withsaid installation controller; and a second sensor sensing the powerdrawn by said second EVSE and communication with said installationcontroller; wherein said installation controller transmits a command tothe first EVSE and a command to the second EVSE to limit the charge ofeach to no more than one-half the current capacity when said first EVSEand said second EVSE are connected for charging; said installationcontroller issuing a restore command to the first EVSE to charge at oneEVSE at a charge limited by the current capacity while the other EVSE isnot connected to an EV or has stopped charging; and said installationcontroller, at a pre-established time after charging a second EVSEevaluating the charge current sent by said first sensor and said secondsensor so that if the charging current of one of the first EVSE or thesecond EVSE is below one-half the current capacity, said installationcontroller transmits a reduce command to the EVSE and an increasecommand to the other of the EVSE to charge each EVSE at a reducedcurrent charge and an increased current charge, respectively.
 11. TheEVSE installation of claim 10 wherein each said first and second currentcontrol has a range of 6 A to 30 A.
 12. The EVSE installation of claim10 wherein said installation controller is disposed at a pay stationmodule or a gateway module.
 13. The EVSE installation of claim 10wherein a said pay station module of a gateway module communicates overa Zigbee multi-network with said first and second EVSE units.
 14. TheEVSE installation of claim 10 wherein said first sensor and said secondsensor each comprise a measuring circuit at said first and said secondEVSE, respectively.
 15. An integrated installation comprising amultiplicity of EVSE installations of claim
 10. 16. The integratedsystem of claim 15 wherein said installation controller controls all ofthe EVSE units.